The invention relates to a process for the preparation of an aromatic hydrocarbon mixture from a mixture of carbon monoxide and hydrogen using a mixture of two catalysts of which one has the capability of catalysing the conversion of an H.sub.2 /CO mixture into acyclic oxygen-containing hydrocarbons, and the other is a crystalline silicate which has the capability of catalysing the conversion of acyclic oxygen-containing hydrocarbons into aromatic hydrocarbons.
It is known to prepare aromatic hydrocarbons from synthesis gas over a mixture of a methanol synthesis catalyst and certain crystalline silicates as disclosed in German patent application No. 2518097 and in U.S. Pat. Nos. 4,086,262 and 4,096,163. However, for commercial application it is highly desirable to employ a process wherein higher selectivity to products boiling in the gasoline range, i.e., pentanes and higher (C.sub.5.sup.+) is achieved.
In an investigation by Applicants concerning the above-mentioned process it was found that the catalyst mixtures show a higher C.sub.5.sup.+ selectivity according as, in the formula hereinafter which shows the composition of the silicate, the value of y is lower. It was found that to reach a C.sub.5.sup.+ selectivity which is acceptable for commercial use of the process, y should be at most 0.005. This finding is the subject of applicants' related Netherlands patent application No. 7811735 and corresponding U.S. patent application Ser. No. 095,025, filed Nov. 16, 1979. Further investigation by Applicants concerning the above-mentioned process has now revealed that also with catalyst mixtures in which a silicate is present whose value of y is greater than 0.005, an acceptable C.sub.5.sup.+ selectivity can be reached, provided that the silicate contains one or more elements selected from the group of manganese, calcium, magnesium and titanium.
The invention therefore relates to a process for the preparation of an aromatic hydrocarbon mixture in which a mixture of carbon monoxide and hydrogen is contacted with a mixture of two catalysts of which one is capable of catalysing the conversion of an H.sub.2 /CO mixture into acyclic oxygen-containing hydrocarbons, and the other is a crystalline silicate as defined above, of which, in the formula giving the composition of the silicate, the value of y is more than 0.005, and which contains one or more elements selected from the group of manganese, calcium, magnesium and titanium.